Television tuner



y 1958 R. WM. SELBMANN ETAL 2,835,818

TELEVISION TUNER Filed Jan. 10, 1955 IN VEN TORS fua/a/f United StatesPatent TELEVISION TUNER Rudolf Wm. Selbmann, Jamaica, Morris L. Tucci,Brooklyn, and Walter Piwinski, Westbury, N. Y., assignors to Oak Mfg.Co., a corporation of Illinois Application January 10, 1955, Serial No.480,918

3 Claims. (Cl. 250-40) This invention relates to a television tuner andmore particularly to a tuner of the rotary switch type. As is wellknown, such a tuner comprises a number of rotary switch sectionsassociated with suitable index means so that the switch may be turned toany one of a number of different positions. The switch sections carrysuitable circuit components such as inductor-s, capacitors and resistorsso that suitable resonant circuits for particular television channelsare provided for each indexed switch position. Thus as an example,switch sections as illustrated in United States Patent No. 2,186,949issued on January 16, 1940, may be used.

This invention provides a construction whereby the size of the tuner maybe reduced and simplified. In addition, this invention provides a novelconstruction for a trimmer or Vernier condenser used for fine tuning.

In order that the invention may be understood, reference will now bemade to the drawing wherein an exemplary embodiment illustrative of theinvention is shown.--- It is understood, however, that variations may bemade without departing from the scope'of the invention except as definedby the appended claims.

Figure 1 is a perspective view with certain parts broken away showing atuner embodying the present invention.

Figure 2 is an end View with certain parts broken away of the tunerillustrated in Figure 1.

Figure 3 is an exploded view of the trimmer condenser and drive.

Figure 4 is a sectional detail on line 4-4 of Figure 1.

The tuner comprises relatively heavy metal housing generally indicatedby and having a generally U shape. While it is possible to make housing10 of one piece, it is convenient to have part 11 and rear panel 12 inone piece with front plate 13 separated from but rigidly attached topart 11 as by bolts, spot welding, or the like. Part 11 of the housingfunctions as a tube shelf upon which some vacuum tube amplifiers andother components may be supported. Housing 10 is provided at the bottomwith metal reinforcing bar 15 extending across from the front to therear panels and rigidly attached to the bottom edges of such panels.

Suitably journaled in plates 12 and 13 is shaft 17. Shaft 17v extendsthrough a number of switch sections generally indicated by 19, suchswitch sections having stator and rotor parts.

Each switch section includes a stator 21 formed of insulating materialcarrying stationary contacts 22 and circuit elements as inductors 23.Stationary contacts 22 are flat strips of metal having spaced radialslots 24 and carrying attached thereto as by eyelets 25 spring contactclips 26. Suitable adjusting screws, coils, and the like are secured tothe various stationary contacts as illustrated in the drawing. Inasmuchas the details of the switch section form no part of the presentinvention, a detailed description thereof will not be given.

Forming part of each switch section is rotor 30 carried on the shaft andhaving suitable rotor contacts 31 for cooperation with the statorcontacts. Thus rotor I contacts 31 generally take the form of flatstrips of metal designed to cooperate with any desired stationarycontact or contacts for switching purposes. The rotor for a switchsection includes an insulating disc carrying the rotor contacts, theinsulating disc having a non-circular aperture therethrough for couplingto the shaft so that the shaft may rotate the rotor disc. The rotorcontacts move between the opposed jaws of the spring contact clips.

Each switch section 19 has stator 21 thereof shaped to provide top andbottom wings 32 and 33. These wings extend through slots in tube shelf11 and reinforcing bar 15 and are tightly wedged therein. By virtue ofthis arrangement, a rigid support for each switch section is provided.

In practice, a complete television tuner may have as many switchsections as are necessary for proper operation, there usually being atleast four and sometimes there being as many 'as five switchingsections. Some switching sections are shielded from the remainingsections as by a metal plate 35 disposed between rear and front panels;12 and 13 respectively.

Any suitable index means for permitting the switch to be indexed fromone position to the other is provided,

, such index means being secured on the shaft and on one of the panels,such as for example on the inside of front panel 13. As an example,spring arm 36 attached to shaft 17 carries ball bearing 38 which ispressed against the inside surface of panel 13. Panel 13 has a number ofapertures 39, smaller than the ball bearing, for defining 'an indexposition. It is understood that the switching sections are so designedthat each index position corresponds to a different switch position.

Fine tuning means are provided, such means consisting of two fixedcondenser plate electrodes having a movable dielectric therebetween. Thedielectric is so selected as to have a high specific dielectric constantso that movement of the dielectric with respect to the electrodes willresult in variation of capacitance.

While the stator portions of switch sections consist of a simple pieceof insulation having two wing portions, the end stator near one of thehousing panels as panel 13 is shaped to have an additional supportportion 41. Stator support portion 41 carries one plate 42 of acondenser. While plate 42 may have any desired shape, the constructionillustrated has been found to be satisfactory. This comprises electrodeportion 43 and three bent supporting portions 44. The supportingportions have small fingers 45 adapted to pass through slots ininsulating stator portion 41. through the stator portion are staked orspread to lock the condenser plate in position on switch stator portion41.

Cooperating with condenser plate 42 is companion con denser plate 47having an electrode portion and having -Dielectricplate 55 of suitablethickness is disposed between the condenser plates, the dielectric platebeing carried in such manner as to be movable in and out of the regionbetween the condenser plates. To this end dielectric plate 55 is carriedby stub shaft 56 rotatively secured in part 57 of grounded cooperatingcondenser plate 47 and in front panel 13. As is clear from Figure 3,condenser plate 42 is shaped to clear the shaft. Dielectric plate 55 issuitably shaped so that upon turning of stub shaft 56, the dielectricplate will be moved in and out of the region between the opposingcondenser plates.

The fingers after passing It is understood that condenser plate 42carried by stator portion 41 is connected in the oscillator section ofthe tuner so that the capacitance of the trimmer condenser will resultin varying the frequency of the oscillator to tune in the desiredchannel. v I

Means for varying the trimmer condenser are provided, such meansincluding a general sector shaped plate 60 attached to stub shaft 56.Finger 51 of the grounded condenser plate is long enough so that it maybe engaged by suitably shaped parts of sector plate 60 to func tion as astop and limit the rotation of this plate. Sector plate 6t extendstoward tuner shaft 17. Control of fine tuning is obtained by a pair ofspring friction washers 63 and carried by sleeve 65 disposed on shaft17. The sleeve may be longitudinally locked to shaft 17 by spring wire 7disposed ina slot in the sleeve and cooperating with an annular groovein shaft 17. Friction washers 63 and 64 are on opposite sides of theedge of sector plate and provide a friction drive between sleeve 65 andthe trimmer condenser stub shaft. Suitable knobs on the tuner shaft andsleeve may be prvided and the tuner shaft knob maycooperatewithindioator means for showing the selected channel.

The fine tuning trimmer condenser may be disposed adjacent the rearpanel of the tuner housing. case, the sleeve over the shaft would beused to operate the switch sections and the solid shaft would carryfriction discs or washers for fine tuning.

What is claimed is:

1. in a rotary switch type tuner for high frequencies, said tunerincluding a rigid metal housing having parallel front and rear metalpanels, a shaft rotatively secured in said front and rear metal panelsand passing through the housing, a plurality of switch sections Withinsaid housing, each switch section including an insulating stator, meansfor rigidly supporting each stator in said housing, each stator having acooperating rotor engaged by the shaft passing through the same, the endstator nearest the front panel carrying a fixed condenser plate havingan electrode portion lying in a plane generally parallel to said panel,a cooperating fixed condenser plate carried by said front panel andhaving an electrode portion disposed parallel to and spaced from saidfirst named condenser plate, a stub shaft journaled for rotation in thefront panel and in the cooperating condenser plate, a dielectric platecarried by said stub shaft and movable thereby between the condenserplates for varying the capacitance thereof, the entire condenser lyingwithin the metal housing, means disposed on the outside of the frontpanel for turning the stub shaft to vary the capaci tance, said endinsulating stator adjacent the front panel having oppositely disposedextensions secured to said housing and having a third extension securedto said housing with said fixed condenser plate secured to said thirdextension so that the same is retained rigidly in position.

2. In a rotary switch type tuner for high frequencies, said tunerincluding a rigid metal housing having parallel front rear metal panels,a shaft rotatively secured in said front and rear panels and passingthrough the housing, a plurality of switch sections within said housing,each switch section including an insulating stator, means for rigidlysupporting each stator in said housing, each stator having a cooperatingrotor engaged by the shaft passing through the same, the end statornearest In such i the front panel carrying a fixed condenser platehaving an electrode portion lying in a plane generally parallel to saidpanel, a cooperating fixed condenser plate carried by said front paneland having an electrode portion disposed parallel to and spaced fromsaid first-named condenser plate, a stub shaft journaled for rotation inthe front panel and in the cooperating condenser plate, a dielectricplate carried by said stub shaft and movable thereby between thecondenser plates for varying the capacitance thereof, the entirecondenser lying within the metal housing, means disposed on the outsideof the front panel for turning the stub shaft to vary the capacitance,said front panel being apertured and the cooperating condenser platehaving fingers extending through said front panel and solderedthereto,said cooperating condenser plate being adjusted with respect tothe front plate to provide a predetermined separation from the fixedcondenser plate prior to soldering, the separation being equal to thethickness of the dielectric plate.

3. In a'ro tary switch type tuner for high frequencies, said tunerincluding a rigid metal housing having parallel front and rear metalpanels, a shaft rotatively secured in said front and rear metal panelsand passing through the housing, a plurality of switch sections withinsaid housing, each switch section including an insulating stator, meansfor rigidly supporting each stator in said housing, each stator having acooperating'rotor engaged by the shaft passing through the same, the endstator nearest the front panel carrying a fixed condenser plate havingan electrode portion lying in a plane generally parallel to said panel,a cooperating fixed condenser plate carried by said front panel andhaving an electrode portion disposed parallel to and spaced from saidfirst-named condenser plate, a stub shaft journaled for rotation in thefront panel and in the cooperating condenser plate, a dielectric platecarried by said stub shaft and movable thereby between the condenserplates for varying the capacitance thereof, the entire condenser lyingwithin the metal housing, means disposed on the outside of the frontpanel for turning the stub shaft to vary the cap-acitance, saidcooperating condenser plate including a number of fingers passingthrough apertures in the front panel, said cooperating condenser platebeing soldered to said front panel after the plate has been disposed indesired position, one of the fingers of said cooperating condenser plateextending through the front panel and functioning'as :a stop finger, asector disc carried by saidstub shaft and having a portion shaped tocooperate with said stop finger for defining a range of angular travelof said stub shaft, a sleeve disposed over said tuner shaft and frictiondiscs on said sleeve and engaging said sector disc on opposite sidesthereof at the edges thereof for driving the same.

References Cited in the file of this patent UNITED STATES PATENTS2,052,882 Krahl Sept. 1, 1936 2,535,686 Lawrence 'Dec. 16, 19502,551,228 Aehenbach May 1, 1951 2,584,120 Fyler Feb. 5, 1952 2,620,378Thias Dec. 2, 1953 2,698,388 Cage Dec. 28, 1954 2,700,730 Prew Jan. 25,1955 2,778,943 Blonder Jan. 22, 1957

